The present invention relates to an improved pulsatile blood pump and more particularly a blood circulating pump which is adapted for surgical heart treatments.
Recently, various extracorporeal heart devices with blood pump have been proposed to circulate the blood through an extracorporeal circuit in an open heart surgery such as a cardiac transplantation.
Hitherto, a blood pump of the type referred to has been arranged so that an elastic sleeve is engaged with a plurality of rollers which turn at a predetermined velocity for squeezing the sleeve to obtain a desired transfer of the blood.
The circulation of the blood should physiologically be pulsatory like the human heart pulsation and in this view a pump of ordinary type which operates at a constant flow rate should not be used to transfer the blood for the prolonged period as it undesirably affects the flow characteristics of the vascular system.
To overcome many difficulties and inconveniences in the conventional blood pumps, it has been proposed for instance to use a reciprocating pump as generally employed in mechanically oriented industry for obtaining a desired pulsatile blood flow or a tube pump in which the turning motion of the roller in engagement with the sleeve pump chamber is variably controlled to obtain a desired pulsatile blood flow.
However, in the reciprocating pump of the type referred to an intricate vascular flow is likely caused with undesired stagnation and oscillation of the blood resulting in developments of undesired blood-destruction (hemolysis) and coagulation. While, the tube pump needs an intricate and uneconomical control means for producing a desired pulsatile blood flow approximate to the physiological pulsation.
Moreover, the blood pump once used must be cleansed and sterilized perfectly. However, the conventional pumps are unsuitable to satisfy such the important medical condition on account of the inconvenient cleansing treatment and the excessive consumption.
Further, prior art pumps are subject to a number of objection and disadvantages for such use. Some have a traumatic effect on the blood cells, some present a problem of sterilization, some produce excessive pulsations of the blood, some cannot be connected into the blood circuit and put into operation quickly and conveniently and some are objectionably complicated and expensive to manufacture.
According to the present invention, a novel pulsatile blood pump which comprises a disposable pump chamber and a pulsating mechanism producing a desired blood flow proximate to the physiological pulsation.
It is, therefore, a general object of the invention to provide a pump of the type described which is relatively simple in structure, inexpensive to manufacture, reliable and essentially trouble free in deterging or sterilizing treatment and enables to produce a pulsatile blood flow substantially proximate to the physiological pulsation.